α1-6 fucosyltransferase

ABSTRACT

PCT No. PCT/JP97/00171 Sec. 371 Date Jan. 7, 1998 Sec. 102(e) Date Jan. 7, 1998 PCT Filed Jan. 23, 1997 PCT Pub. No. WO97/27303 PCT Pub. Date Jul. 31, 1997Porcine- or human-derived  alpha 1-6 fucosyltransferases having the following action: action: transferring fucose from guanosine adiphosphate-fucose to the hydroxy group at 6-position of GlcNAc closest to R of a receptor (GlcNAc beta 1-2Man alpha 1-6)(GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc-R wherein R is an asparagine residue or a peptide chain carrying said residue, whereby to form (GlcNAc beta 1-2Man alpha 1-6)-(GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4(Fuc alpha 1-6)GlcNAc-R; a gene encoding these enzymes; an expression vector containing the gene; a transformant prepared by using this expression vector; and a method for producing a recombinant  alpha 1-6 fucosyltransferase, by culturing the transformant.

This application is the National Stage of PCT/JP97/00171, filed Jan. 23, 1997.

TECHNICAL FIELD

The present invention relates to an α1-6 fucosyltransferase derived from pig or human. More particularly, the present invention relates to a novel α1-6 fucosyltransferase derived from human, which is an enzyme that transfers fucose from guanosine diphosphate (GDP)-fucose by α1→6 linkage to N-acetylglucosamine (GlcNAc) bound to Asn at the stem of asparagine type sugar chain (Asn type sugar chain) and which is useful in the field of glyco-technology for modification and synthesis of sugar chain and/or for the diagnosis of diseases such as malignant tumor, and to a gene encoding said enzyme.

BACKGROUND ART

The structure and function of sugar chain moiety of complex carbohydrates, such as glycoprotein and glycolipid, derived from higher organisms have been drawing much attention in recent years, and many studies are under way. While a sugar chain is formed by the action of glycohydrolase and glycosyltransferase, glycosyltransferase contributes greatly to its formation.

Using a sugar nucleotide as a sugar donor, glycosyltransferase transfers a sugar to a receptor sugar chain, thereby to elongate the sugar chain. The specificity for the structure of receptor sugar chain is stringent, such that one glycoside linkage is formed by the corresponding one transferase. Hence, glycosyltransferases are used for structural studies of sugar moiety of complex carbohydrate, for facilitated synthesis of a particular sugar chain structure, and for modification of native sugar chain structure.

Besides, glycosyltransferases are expected to be usable for the modification of the nature of complex carbohydrate and cells, by means of artificial alteration of sugar chain. For this end, the development of various glycosyltransferases having identified substrate specificity has been awaited.

An α1-6 fucosyltransferase is an important enzyme found in Golgi appratus of organelle, which is considered to be one of the enzymes that control processing of asparagine-linked sugar chain. Therefore, the enzyme will be useful for the elucidation of control mechanism and control of formation of sugar chain structure, once acted on an asparagine-linked sugar chain.

In addition, the activity of α1-6 fucosyltransferase and the proportion of reaction products of this enzyme are known to increase in certain diseases such as liver cancer and cystic fibrosis. Therefore, a rapid development of the method for diagnosis of these diseases has been desired, which involves determination of the activity of this enzyme, Northern blot using a cDNA encoding α1-6 fucosyltransferase, or RT-PCR assay of mRNA amount transcribed and expressed in the living body.

The activity of α1-6 fucosyltransferases has been detected in body fluids or organs of various animals and culture cells thereof, and there has been known, as a purified enzyme product, an enzyme derived from human cystic fibrosis cell homogenates [Journal of Biological Chemistry, vol. 266, pp. 21572-21577 (1991)]. According to this report, however, the enzyme is associated with drawbacks in that (1) its optimum pH is 5.6 which is different from physiological pH, (2) it has relatively low molecular weights (34,000 and 39,000) by SDS-polyacrylamide gel electrophoresis, (3) its large scale and stable supply is practically unattainable due to its being derived from human cell, and others.

This enzyme is obtained as a membrane-bound enzyme, and requires bovine serum for culturing the cells, which in turn results in difficult purification of the enzyme and a huge amount of money necessary for culture of the cells to be a starting material. Consequently, stable supply of this enzyme preparation is all but impractical.

While a chemical synthesis is often employed for synthesizing a sugar chain, the synthesis of oligosaccharides requires many steps that have been necessitated by its complicated synthesis route and specificity of the reaction, so that it involves various practical problems. Particularly, binding of fucose to GlcNAc bound to Asn of asparagine-linked sugar chain by α1→6 linkage is extremely difficult due to the instability of fucose.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to stably provide an α1-6 fucosyltransferase in large amounts, which is useful as a reagent for structural analysis of sugar chain or glyco-technology, or as diagnostics.

Another object of the present invention is to provide a method of producing α1-6 fucosyltransferase in large amounts by the use of a human- or porcine-derived α1-6 fucosyltransferase gene. It is aimed to use such specific genes so as to enable development of a method for diagnosis of diseases by Northern blot using a DNA encoding said enzyme, or by RT-PCR assay of mRNA amount transcribed and expressed in the living body.

In an attempt to achieve the above-mentioned objects, the present inventors started the study of an enzyme capable of linking fucose to GlcNAc linked to Asn of asparagine type sugar chain by α1→6 linkage, using a fluorescence-labeled substrate analogous to an asparagine type sugar chain which is a receptor of this enzyme. As a result, they have found the activity of this enzyme in the extract fractions of porcine brain which is readily available as a starting material to be purified, and they have purified said enzyme from said fractions and elucidated the enzymatic and physico-chemical properties, which resulted in the completion of the invention.

Accordingly, the present invention relates to a porcine-derived α1-6 fucosyltransferase having the following physico-chemical properties (hereinafter this enzyme is referred to as porcine α1-6 fucosyltransferase).

(1) Action: transferring fucose from guanosine diphosphate-fucose to the hydroxy group at 6-position of GlcNAc closest to R of a receptor (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAcβ1-4GlcNAc-R wherein R is an asparagine residue or a peptide chain carrying said residue, whereby to form (GlcNAcβ1-2Manα1-6)-(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc-R.

In the above formula, asparagine residue at R is a residue wherein the acid amide group at the side chain of asparagine is bound to the hydroxy group at the anomer position of the reducing terminal of sugar chain, and a peptide chain having said residue is a peptide chain having said residue in the peptide to which two or more amino acids are bound, which is preferably a peptide chain having --Asn--(X)--Ser/Thr--.

(2) optimum pH: about 7.0

(3) pH stability: stable in the pH range of 4.0-10.0 by treatment at 4° C. for 5 hours

(4) optimum temperature: about 30-37° C.

(5) inhibition or activation: no requirement for divalent metal ion for expression of activity; no inhibition of activity even in the presence of 5 mM EDTA

(6) molecular weight : about 60,000 by SDS-polyacrylamide gel electrophoresis.

The present inventors have purified α1-6 fucosyltransferase alone from porcine brain, analyzed the amino acid sequence of this protein and cloned a gene based on the partial amino acid sequence to accomplish the present invention.

That is, the present invention provides a gene encoding porcine α1-6 fucosyltransferase.

The present invention also provides an expression vector containing a gene encoding porcine α1-6 fucosyltransferase.

The present invention further provides a transformant cell obtained by transforming a host cell with an expression vector containing a gene encoding porcine α1-6 fucosyltransferase.

The present invention yet provides a method for producing a recombinant α1-6 fucosyltransferase, comprising culturing a transformant cell obtained by transforming a host cell with an expression vector containing a gene encoding porcine α1-6 fucosyltransferase, and harvesting the α1-6 fucosyltransferase from the culture thereof.

The present inventors have reached the present invention by purifying protein having an α1-6 fucosyltransferase activity from human cell culture broth and elucidating its enzymatic property.

Accordingly, the present invention relates to an α1-6 fucosyltransferase derived from human, having the following physico-chemical property (hereinafter this enzyme is to be referred to as human α1-6 fucosyltransferase).

(1) Action: transferring fucose from guanosine diphosphate-fucose to the hydroxy group at 6-position of GlcNAc closest to R of a receptor (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-R wherein R is an asparagine residue or a peptide chain carrying said residue, whereby to form (GlcNAcβ1-2Manα1-6)-(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc-R.

In the above formula, asparagine residue at R is a residue wherein the acid amide group at the side chain of asparagine is bound to the reducing terminal hydroxy group of sugar chain, and a peptide chain having said residue is a peptide chain having said residue in the peptide to which two or more amino acids are bound, which is preferably a peptide chain having --Asn--(X)--Ser/Thr--.

(2) optimum pH: about 7.5

(3) pH stability: stable in the pH range of 4.0-10.0 by treatment at 4° C. for 5 hours

(4) optimum temperature: about 30-37° C.

(5) inhibition or activation: no requirement for divalent metal ion for expression of activity; no inhibition of activity even in the presence of 5 mM EDTA

(6) molecular weight: about 60,000 by SDS-polyacrylamide gel electrophoresis.

The present inventors have purified α1-6 fucosyltransferase alone from human culture cell, analyzed the amino acid sequence of this protein and cloned a gene based on the partial amino acid sequence to accomplish the present invention.

That is, the present invention provides a gene encoding human α1-6 fucosyltransferase.

The present invention also provides an expression vector containing a gene encoding human α1-6 fucosyltransferase.

The present invention further provides a transformant cell obtained by transforming a host cell with an expression vector containing a gene encoding human α1-6 fucosyltransferase.

The present invention yet provides a method for producing a recombinant α1-6 fucosyltransferase, comprising culturing a transformant cell obtained by transforming a host cell with an expression vector containing a gene encoding human α1-6 fucosyltransferase, and harvesting the α1-6 fucosyltransferase from the culture thereof.

The starting material for the purification of the enzyme of the present invention is, for example, the organ and body fluid of pig having α1-6 fucosyltransferase activity. Examples of the organ include brain, spermary, pancreas, lung, kidney and the like. The body fluid of pig such as blood and sera can be also used.

The porcine α1-6 fucosyltransferase of the present invention can be obtained by preparing a crude extract containing the enzyme from, for example, homogenates of porcine brain and separating the enzyme from this extract. In this case, since α1-6 fucosyltransferase in the porcine brain is a membrane-bound enzyme, a crude extract solution containing the enzyme is generally obtained from brain lysate using a suitable surfactant. This extract undergoes various known purification steps to give a purified enzyme product. The purification may include, for example, concentration using an ultrafiltration membrane, desalting, affinity column chromatography wherein a substrate analog is immobilized, ion exchange column chromatography, hydrophobic column chromatography and the like in suitable combination to give a substantially homogeneous enzyme product which is free of contaminant proteins such as other transferases. For example, porcine brain is disrupted in a Waring blender in a phosphate buffer and membrane fractions are collected by ultracentrifugation. The objective enzyme is extracted with a phosphate buffer containing a surfactant (Triton X-100), and the supernatants are collected by ultracentrifugation to give a crude extract containing the enzyme. By applying affinity column chromatography using a guanosine diphosphate (GDP)-hexanolamine-sepharose, a GlcNAcβ1-2Manα1-6(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-asparagine-sepharose and the like, the fractions showing fucosyltransferase activity are collected and purified.

The physico-chemical property of α1-6 fucosyltransferase derived from porcine brain, which is one aspect of the present invention, is as follows.

(1) Action: transferring fucose from guanosine diphosphate-fucose to the hydroxy group at 6-position of GlcNAc closest to R of a receptor (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-R wherein R is an asparagine residue or a peptide chain carrying said residue, whereby to form (GlcNAcβ1-2Manα1-6)-(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc-R.

(2) Determination of activity:

The activity of the porcine α1-6 fucosyltransferase was determined as follows. That is, a compound of the following formula, wherein the sugar chain end asparagine was fluorescence-labeled with 4-(2-pyridylamino)butylamine [PABA: --NH₂ (CH₂)₄ --NH-pyridine] was used as a substrate for determination of enzyme activity: ##STR1## wherein PA means pyridylamino. By the use of this substrate, the product from the enzyme reaction, wherein fucose has been transferred by α1→6 linkage, can be assayed by detecting fluorescence by high performance liquid chromatography.

Specifically, the determination includes the following steps. A sample solution (10 μl) and 1.25% Triton X-100 are added to a 250 mM MES buffer containing 62.5 μM of fluorescence-labeled receptor substrate of the above formula and 625 μM of a donor substrate (GDP-fucose), pH 7.0, 40 μl, and mixed. The mixture is reacted at 37° C. for one hour, and boiled for 5 minutes to stop the reaction. The reaction mixture is subjected to high performance liquid chromatography and the peak of the reaction product is assayed with a fluorescence detector. One unit of the enzyme amount corresponds to the amount capable of forming 1 pmole of GlcNAc β1-2Manα1-6(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAc.beta.1-4(Fucα1-6)GlcNAc-R (wherein R is Asn-NH--(CH₂)₄ --NH-pyridine) in one minute under these conditions.

(3) Optimum pH:

The α1-6 fucosyltransferase derived from porcine brain (hereinafter this enzyme is referred to as porcine brain α1-6 fucosyltransferase) shows a high activity at nearly pH 7.0-7.5.

(4) pH Stability:

The porcine brain α1-6 fucosyltransferase is relatively stable at pH 4-10, and more stable at pH 5-9.

(5) Optimum temperature:

The porcine brain α1-6 fucosyltransferase has an optimum temperature at nearly 37° C. and retains sufficient activity at 20-40° C.

(6) Divalent metal ion requirement:

The porcine brain α1-6 fucosyltransferase shows sufficient activity even in the absence of divalent metal ion, such as magnesium, manganese and the like. It also shows sufficient activity even in the presence of 5 mM EDTA, which is a chelating agent.

(7) Molecular weight:

A purified product of the porcine brain α1-6 fucosyltransferase shows a single band at a molecular weight of about 60,000 by SDS-polyacrylamide gel electrophoresis.

Judging from the above properties, the porcine brain α1-6 fucosyltransferase is a novel enzyme apparently different from conventionally known α1-6 fucosyltransferase derived from human cystic fibrosis cells (optimum pH 5.6, molecular weights 34,000 and 39,000), in terms of optimum pH, metal ion requirement and molecular weight.

The inventive porcine α1-6 fucosyltransferase is expected to be extremely useful for (1) synthesis of sugar chain compounds wherein sugar chain compounds having 1-6 fucose are synthesized using the enzyme of the present invention, (2) modification of sugar chain structure and functional analysis wherein a fucose is newly introduced into asparagine type sugar chain to artificially modify the sugar chain structure, whereby changes in cell function and control mechanism of the processing of complex carbohydrate, as well as the role of sugar chain, can be elucidated, (3) diagnosis of lesions based on enzyme activity wherein diseases such as cancer can be diagnosed by determining the activity of the enzyme of the present invention which reflects various lesions caused by tumorigenic transformation, (4) diagnosis of various diseases wherein a specific antibody against the enzyme of the present invention is prepared and used for the diagnosis, and the like.

Another aspect of the present invention is a gene encoding porcine α1-6 fucosyltransferase, which includes a gene encoding α1-6 fucosyltransferase and including a gene encoding amino acid sequence depicted in Sequence Listing, SEQ ID NO:2. A different embodiment thereof is a gene encoding α1-6 fucosyltransferase and including nucleotide sequence depicted in Sequence Listing, SEQ ID NO:1.

One aspect of the present invention is a gene encoding porcine α1-6 fucosyltransferase and including a gene encoding an amino acid sequence resulting from substitution, insertion, deletion or addition with respect to at least one amino acid of the amino acid sequence depicted in Sequence Listing, SEQ ID NO:2.

Another aspect of the present invention is a gene encoding porcine α1-6 fucosyltransferase and including a nucleotide sequence resulting from substitution, insertion, deletion or addition with respect to at least one nucleotide of the nucleotide sequence depicted in Sequence Listing, SEQ ID NO:1.

The present invention also includes, as one aspect thereof, a gene that hybridizes to at least a part of a gene encoding porcine α1-6 fucosyltransferase and including nucleotide sequence depicted in Sequence Listing, SEQ ID NO:1.

The expression vector of the present invention contains a gene encoding the above-mentioned porcine α1-6 fucosyltransferase.

The transformant host cell of the present invention has been transformed with the above-mentioned expression vector.

The host cell is exemplified by microorganisms, such as Escherichia coli, yeast, bacterial cells and the like. It also includes animal cells such as insect cells, COS-1 cells, CHO cells and the like, and plant cells, such as tobacco cells, Arabidopsis cells and the like.

The vector may be any which is selected according to the host to be transformed. In the case of Escherichia coli, for example, pUC19 may be used; in the case of yeast, pYEUra3™ may be used; in the case of insect cells, pBLUE Bac4 may be used; in the case of COS-1 cells, pSVK3 may be used; and in the case of tobacco cells and Arabidopsis cells, pBI may be used.

The method for preparing the inventive recombinant α1-6 fucosyltransferase includes culturing the above-mentioned transformant cells and harvesting α1-6 fucosyltransferase from the culture.

According to the present invention, α1-6 fucosyltransferase alone is purified from porcine brain, and subjected to amino acid analysis of this protein. Its partial amino acid sequence is determined and a primer for PCR is prepared based on the amino acid sequence. Using this primer, PCR is performed using cDNAs derived from porcine brain as a template to amplify a gene encoding α1-6 fucosyltransferase to give a probe. This probe is used to screen clones containing cDNA encoding α1-6 fucosyltransferase, from the cDNA library derived from porcine brain. The cDNA encoding α1-6 fucosyltransferase is isolated and used to express α1-6 fucosyltransferase.

To be specific, the purified porcine α1-6 fucosyltransferase is used to analyze amino acid sequences. For example, SDS-polyacrylamide gel electrophoresis is applied, after which the protein is transferred to PVDF membrane by electroblotting, and the PVDF membrane containing ca. 60 kDa band is cut out and subjected to sequencing using a protein sequencer. As a result, the amino acid sequence of the amino terminal of α1-6 fucosyltransferase depicted in Sequence Listing, SEQ ID NO:3 is obtained.

Separately, purified α1-6 fucosyltransferase is subjected to SDS-polyacrylamide gel electrophoresis and the peptide fragments separated by electrophoresis are transferred to PVDF membrane by electroblotting. Then, the PVDF membrane containing 60 kDa band is cut out and lysed on said PVDF membrane, using, for example, a protease such as lysylendopeptidase. The lysate is extracted from the sections of said PVDF membrane, and the extract is subjected to reversed phase high performance liquid chromatography to separate the lysate.

Then, using the amino acid sequences, a mixed primer for PCR is prepared. For example, a mixed primer having a nucleotide sequence depicted in SEQ ID NO:7 is synthesized from the amino acid sequence depicted in SEQ ID NO:3, and a mixed primer having a nucleotide sequence depicted in SEQ ID NO:8 is synthesized from the amino acid sequence depicted in SEQ ID NO:4, respectively using a DNA synthesizer, and used for the screening of cDNA of α1-6 fucosyltransferase.

For example, 25 cycles of PCR are performed to amplify DNA fragments of ca. 1.45 kbp, using cDNA from porcine brain as a template and mixed primers of SEQ ID NO:7 and SEQ ID NO:8, wherein PCR at 94° C. (1 min), 55° C. (2 min) and 72° C. (3 min) is one cycle.

Then, using the amplified DNA fragments as a probe, clones containing cDNA encoding α1-6 fucosyltransferase are screened from the cDNA library derived from porcine brain by a plaque hybridization method. The cDNA encoding α1-6 fucosyltransferase can be isolated from the obtained clones. The nucleotide sequence of the obtained cDNA and the amino acid sequence deduced from said nucleotide sequence are shown in SEQ ID NO:1 and SEQ ID NO:2.

Said cDNA is subcloned into an expression vector such as pSVK3. The host cells, such as COS-1 cells, transformed with said subcloned plasmid, are cultured and α1-6 fucosyltransferase is obtained from the culture.

In the present invention, the above-mentioned transformant cells are cultured and α1-6 fucosyltransferase is harvested from the culture, whereby recombinant α1-6 fucosyltransferase is obtained. The method for harvesting the enzyme from the culture is a conventional one.

The gene encoding the porcine α1-6 fucosyltransferase of the present invention and DNA fragments (which are the lysates thereof) may be used for the detection of the expression of α1-6 fucosyltransferase in the living body, and thus are useful for the genetic diagnosis of certain diseases such as liver cancer and cystic fibrosis.

In addition, the polypeptide that is encoded by these genes can be used to immunologically prepare various antibodies which are useful for diagnosis and purification of α1-6 fucosyltransferase.

The starting material for the purification of the enzyme in this invention may be any as long as it is a human cell culture medium exhibiting α1-6 fucosyltransferase activity. For example, human pancreatic cancer cells, human gastric cancer cells, human myeloma tumor cells and the like may be used as the cells having α1-6 fucosyltransferase activity.

While the human α1-6 fucosyltransferase is present in the cell membrane as a membrane-bound enzyme, it is cleaved by protease at a site unaffecting the enzyme activity and released into the culture medium as a soluble enzyme. Thus, the culture medium can be used as a crude enzyme solution, without complicated steps such as disruption of cells and solubilizing of the enzyme. Besides, the use of cells capable of growth in serum-free media enables economical production of a crude enzyme solution having a high purity. The culture medium is concentrated and desalted, and subjected to ion exchange chromatography, affinity chromatography and the like to give a purified enzyme product free of contaminant transferases and glycosidase activity.

α1-6 Fucosyltransferase is purified from human gastric cancer cells by, for example, culturing human gastric cancer cell MKN45 without serum and purifying the enzyme from the obtained culture medium. In this case, α1-6 fucosyltransferase of human gastric cancer cell MKN45 is cleaved by protease in the cells at a site unaffecting the enzyme activity and released into culture medium as a soluble α1-6 fucosyltransferase. Therefore, the culture medium can be used as a crude enzyme solution, without complicated steps such as disruption of cells and solubilizing of the enzyme with a surfactant. The crude enzyme solution is subjected to known purification steps to give a purified enzyme product.

In the present invention, a serum-free culture medium of human gastric cancer cell MKN45 is concentrated by filtration through an ultrafiltration membrane, and then the buffer is changed to a Tris-HCl buffer containing 5 mM 2-mercaptoethanol and 0.1% CHAPS [3-((3-cholamidopropyl)dimethylammonio)-1-propanesulfonate], pH 7.5, to give a crude enzyme solution.

This enzyme solution is subjected to column chromatography using Q-sepharose, GDP-hexanolamine-sepharose, (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-asparagine-sepharose and the like to collect active fractions, from which the fucosyltransferase of the present invention can be purified.

The physico-chemical property of human α1-6 fucosyltransferase of the present invention is as follows.

(1) Action: transferring fucose from guanosine diphosphate-fucose to the hydroxy group at 6-position of GluNAc closest to R of a receptor (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-R wherein R is an asparagine residue or a peptide chain carrying said residue, whereby to form (GlcNAcβ1-2Manα1-6)-(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc-R.

(2) Determination of enzyme activity:

The activity of the human α1-6 fucosyltransferase was determined as follows. That is, a compound of the above-mentioned formula, wherein the asparagine on the end of sugar chain was fluorescence-labeled with 4-(2-pyridylamino)butylamine [PABA: --NH₂ (CH₂)₄ --NH-pyridine], was used as a substrate for determination of enzyme activity. By the use of this substrate, the product from the enzyme reaction, wherein fucose is transferred by α1→6 linkage, can be assayed by detecting fluorescence by high performance liquid chromatography.

Specifically, the determination included the following steps. An enzyme solution (10 μl) was added to a 250 mM MES buffer containing 62.5 μM of fluorescence-labeled receptor substrate of the above formula and 625 μM of a donor substrate (GDP-fucose), pH 7.0, 40 μl, and mixed. The mixture was reacted at 37° C. for one hour, and boiled for 5 minutes to stop the reaction. The reaction mixture is subjected to high performance liquid chromatography and the peak of the reaction product is assayed with a fluorescence detector.

One unit of the enzyme amount corresponded to the amount capable of producing 1 pmole of GlcNAcβ1-2Manα1-6(GlcNAcβ1-2Manα1-3)-Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc-R (wherein R is Asn-NH-(CH₂)₄ --NH-Pyridine) in one minute under these conditions.

(3) Optimum pH:

The human α1-6 fucosyltransferase shows high activity at nearly pH 7.0-7.5, as shown by a curve in FIG. 1. In FIG. 1, the determination was performed using 500 mM MES buffer (black circle) at pH 4.5-7.5 and 100 mM Tris-HCl buffer (white circle) at pH 7.0-9.0.

(4) pH Stability:

The human α1-6 fucosyltransferase is stable at about pH 4-10, particularly at pH 5-9, as shown in FIG. 2. The buffers used for the determination were 50 mM acetate buffer (black triangle) at pH 3.5-5.5, 50 mM MES buffer (black circle) at pH 5.5-7.5, 50 mM Tris-HCl buffer (white circle) at pH 7.5-9.0, and sodium hydrogencarbonate buffer (white triangle) at pH 9.0-11.5. The enzyme of the present invention was treated in each buffer at each pH at 4° C. for 5 hours, and the residual activity was determined. FIG. 1 is a graph showing the relationship between pH (axis of abscissa) and relative activity (%, axis of ordinate) of the human α1-6 fucosyltransferase obtained by the present invention, and FIG. 2 is a graph showing pH (axis of abscissa) and residual activity (%, axis of ordinate).

(5) Optimum temperature:

The human α1-6 fucosyltransferase has an optimum temperature at nearly 37° C. as shown in FIG. 3 and is usable at 20-40° C. A frozen product thereof is stable at -20° C. for at least several months.

(6) Divalent metal ion requirement:

Many glycosyltransferases require divalent metal ion for their activity, such as magnesium, manganese and the like. This human α1-6 fucosyltransferase shows sufficient activity in the absence of divalent metal ion or in the presence of EDTA, which is a chelating agent, and does not require divalent metal ion.

(7) Molecular weight:

A purified product of the human α1-6 fucosyltransferase of the present invention shows a single band at a molecular weight of about 60,000 by SDS-polyacrylamide gel electrophoresis.

(8) Morphology:

While the human α1-6 fucosyltransferase is intrinsically present in cell membrane as a membrane-bound enzyme, it is cleaved by protease in the cultured cell at a site unaffecting the enzyme activity and released into a culture medium as a soluble enzyme permitting easy handling, unlike porcine-derived α1-6 fucosyltransferase and α1-6 fucosyltransferase derived from human cystic fibrosis cells heretofore reported.

Judging from the above properties, the human α1-6 fucosyl-transferase is a novel enzyme apparently different from conventionally known α1-6 fucosyltransferase derived from human cystic fibrosis cells (optimum pH 6.5, molecular weights 34,000 and 39,000), in terms of optimum pH, metal requirement and molecular weight.

The human α1-6 fucosyltransferase is used for the following purposes.

(1) Artificial modification of sugar chain structure by introducing fucose anew into the asparagine-linked sugar chain, whereby cell apparatus and control mechanism of processing of sugar chain of complex carbohydrate, as well as the role of sugar chain, can be elucidated.

(2) Diagnosis of various diseases based on the activity of the inventive enzyme.

(3) Diagnosis of various diseases wherein a specific antibody against the enzyme of the present invention is prepared and used for the diagnosis.

The present invention is a gene encoding human α1-6 fucosyl-transferase, which includes, as one embodiment, a gene encoding α1-6 fucosyltransferase and including a gene encoding an amino acid sequence depicted in Sequence Listing, SEQ ID NO:10. A different embodiment thereof is a gene encoding α1-6 fucosyltransferase inclusive of nucleotide sequence depicted in Sequence Listing, SEQ ID NO:9. A further aspect of the present invention is a gene encoding α1-6 fucosyltransferase and including a nucleotide sequence from 198th adenine to 1919th guanine as depicted in Sequence Listing, SEQ ID NO:9.

One aspect of the present invention is a gene encoding α1-6 fucosyltransferase and including a gene encoding an amino acid sequence resulting from substitution, insertion, deletion or addition with respect to at least one amino acid of the amino acid sequence depicted in Sequence Listing, SEQ ID NO:10.

Another aspect of the present invention is a gene encoding α1-6 fucosyltransferase and including a nucleotide sequence resulting from substitution, insertion, deletion or addition with respect to at least one nucleotide of the nucleotide sequence depicted in Sequence Listing, SEQ ID NO:9.

The present invention also includes, as one embodiment, a gene which hybridizes to at least a part of gene encoding α1-6 fucosyltransferase and including nucleotide sequence depicted in Sequence Listing, SEQ ID NO:9.

The expression vector of the present invention contains a gene encoding the above-mentioned α1-6 fucosyltransferase.

The transformant host cell of the present invention has been transformed with the above-mentioned expression vector.

The host cell is exemplified by microorganisms, such as Escherichia coli, yeast, bacterial cells and the like. It also includes animal cells such as insect cells, COS-1 cells, CHO cells and the like, and plant cells, such as tobacco cells, Arabidopsis cells and the like.

The vector may be any which is selected according to the host to be transformed. In the case of Escherichia coli, for example, pUC19 may be used; in the case of yeast, pYEUra™ may be used; in the case of insect cells, pBLUE Bac4 may be used; in the case of COS-1 cells, pSVK3 may be used; and in the case of tobacco cells and Arabidopsis cells, pBI may be used.

The method for preparing the recombinant α1-6 fucosyltransferase includes culturing the above-mentioned transformant cells and harvesting α1-6 fucosyltransferase from the culture.

According to the present invention, α1-6 fucosyltransferase alone is purified from human gastric cancer cells, and subjected to amino acid analysis of this protein. Its partial amino acid sequence is determined and a primer for PCR is prepared based on the amino acid sequence. Using this primer, PCR is performed using cDNAs derived from human gastric cancer cells as a template to amplify a gene encoding α1-6 fucosyltransferase to give a probe. This probe is used to screen clones containing cDNA encoding α1-6 fucosyltransferase, from the cDNA library derived from human gastric cancer cells. The cDNA encoding α1-6 fucosyltransferase is isolated and used to express α1-6 fucosyltransferase.

To be specific, the purified α1-6 fucosyltransferase is used to analyze amino acid sequence. For example, it is subjected to SDS-polyacrylamide gel electrophoresis, after which the protein is transferred to PVDF membrane by electroblotting, and the PVDF membrane containing ca. 60 kDa band is cut out and subjected to sequencing by a protein sequencer. As a result, the amino acid sequence of the amino terminal of α1-6 fucosyltransferase depicted in Sequence Listing, SEQ ID NO:11 is obtained.

Separately, purified α1-6 fucosyltransferase is subjected to SDS-polyacrylamide gel electrophoresis, along with a protease such as lysylendopeptidase, and the peptide fragments separated by electrophoresis are transferred to PVDF membrane by electroblotting. Then, the band containing the peptide fragments is cut out and subjected to sequencing with a protein sequencer. Thus, partial amino acid sequences of α1-6 fucosyltransferase as depicted in Sequence Listing, SEQ ID NO:12 and SEQ ID NO:13 are obtained. Then, using these amino acid sequences, a mixed primer for PCR is prepared. For example, a mixed primer having a nucleotide sequence depicted in SEQ ID NO:14 is synthesized from the amino acid sequence depicted in SEQ ID NO:12, and a mixed primer having a nucleotide sequence depicted in SEQ ID NO:15 is synthesized from the amino acid sequence depicted in SEQ ID NO:13, respectively using a DNA synthesizer, and used for the screening of cDNA of α1-6 fucosyltransferase.

For example, 36 cycles of PCR are performed to amplify the DNA fragments of ca. 200 bp, using cDNA from human gastric cancer cells as a template and mixed primers of SEQ ID NO:14 and SEQ ID NO:15, wherein PCR at 94° C. (30 sec), 46° C. (30 sec) and 72° C. (1.5 min) is one cycle.

Then, using the amplified DNA fragments as a probe, clones containing cDNA encoding α1-6 fucosyltransferase are screened from the cDNA library derived from human gastric cancer cells by a plaque hybridization method. The cDNA encoding α1-6 fucosyltransferase can be isolated from the obtained clones. The nucleotide sequence of the obtained cDNA and the amino acid sequences deduced from said nucleotide sequence are shown in SEQ ID NO:9 and SEQ ID NO:10.

Said cDNA is subcloned into an expression vector such as pSVK3. The host cells such as COS-1 cells transformed with said subcloned plasmid are cultured and α1-6 fucosyltransferase is obtained from the culture.

In the present invention, the above-mentioned transformant cells are cultured and α1-6 fucosyltransferase is harvested from the culture, whereby a recombinant α1-6 fucosyltransferase is obtained.

The method for harvesting the enzyme from the culture is a conventional one.

The gene encoding the human α1-6 fucosyltransferase of the present invention and DNA fragments (which are the lysates thereof) may be used for the determination of the expression of α1-6 fucosyltransferase in the living body and thus are useful for genetic diagnosis of certain diseases such as liver cancer and cystic fibrosis.

In addition, the polypeptide that is encoded by these genes can be used to immunologically prepare various antibodies which are useful for diagnosis and purification of α1-6 fucosyltransferase.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows optimum pH of the porcine brain α1-6 fucosyltransferase of the present invention.

FIG. 2 shows pH stability of the porcine brain α1-6 fucosyltransferase of the present invention.

FIG. 3 shows optimum temperature of the porcine brain α1-6 fucosyltransferase of the present invention.

FIG. 4 shows optimum pH of the human α1-6 fucosyltransferase of the present invention.

FIG. 5 shows pH stability of the human a1-6 fucosyltransferase of the present invention.

FIG. 6 shows optimum temperature of the human α1-6 fucosyltransferase of the present invention.

EMBODIMENT OF THE INVENTION

The present invention is described in more detail by way of Examples.

In the present invention, the enzyme activity is determined as follows.

A compound of the following formula, wherein the asparagine on the end of sugar chain had been fluorescence-labeled with 4-(2-pyridylamino)butylamine [PABA: --NH(CH₂)₄ --NH-pyridine] was used as a substrate for the determination of enzyme activity. ##STR2## By the use of this substrate, the product from the enzyme reaction wherein fucose has been transferred by α1→6 linkage can be assayed by detecting the fluorescence by high performance liquid chromatography.

Specifically, the determination includes the following steps. A sample solution (10 μl) and 1.25% Triton X-100 are added to a 250 mM MES buffer containing 62.5 μM of fluorescence-labeled receptor substrate of the above formula and 625 μM of a donor substrate (GDP-fucose), pH 7.0, 40 μl, and mixed. The mixture is reacted at 37° C. for one hour, and boiled for 5 minutes to stop the reaction. The reaction mixture is subjected to high performance liquid chromatography and the peak of the reaction product is assayed with a fluorescence detector. One unit of the enzyme amount corresponds to the amount capable of producing 1 pmole of GlcNAcβ1-2Manα1-6(GlcNAcβ1-2Manα1-3)-Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc-R (wherein R is Asn-NH--(CH₂)₄ --NH-pyridine) in one minute under these conditions.

EXAMPLE 1

(1) Preparation of porcine brain lysate and crude extract solution

Porcine brain (100 g) was disrupted in a Waring blender in a 20 mM potassium phosphate buffer (pH 7.0) and membrane fractions were collected by ultracentrifugation. The membrane fractions were extracted with the same buffer containing Triton X-100 (concentration 0.5%) to extract the enzyme. After the extraction, the supernatants were collected by centrifugation to give an extract containing a crude enzyme.

(2) Purification of enzyme from crude extract solution

A GlcNAcβ1-2Manα1-6(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-asparagine-sepharose column (column of asialoagalactoglyco-peptide derived from transferring was equilibrated with a 20 mM potassium phosphate buffer (pH 7.0) containing 0.05% Triton X-100 and 50 mM KCl, and the crude extract solution prepared in (1) above was applied. The column was washed with said buffer until the protein was not detected in the unadsorbed fractions. The active fractions were eluted with the same buffer containing 1M KCl. Then, the active fractions of the enzyme were concentrated using an ultrafiltration membrane and desalted, and applied to a GDP-hexanolamine-sepharose column equilibrated with the same buffer. The elution was performed using the same buffer containing 100 mM GDP. Then, the active fractions were collected and concentrated using an ultrafiltration membrane, and desalted to give porcine brain α1-6 fucosyltransferase. The porcine brain α1-6 fucosyltransferase thus obtained showed a single band at a molecular weight of about 60,000 by SDS-polyacrylamide gel electrophoresis. No other bands ascribed to impurities were found and the enzyme was free of other transferase activities, thus indicating that the enzyme obtained was highly purified.

The optimum pH (determined by changing the pH of buffer) of the enzyme of the present invention is shown in FIG. 1. The enzyme showed high activity at around pH 7.0-7.5. The buffer used was 200 mM MES buffer (black circle). In this graph, the axis of abscissa shows pH of α1-6 fucosyltransferase obtained in the present invention and the axis of ordinate shows relative activity (%).

The pH stability of the enzyme of the present invention was examined in the same manner. FIG. 2 shows residual activity after treating the enzyme in each buffer at each pH, 4° C. for 5 hours. The enzyme was comparatively stable at about pH 4-10, and particularly stable at pH 5-9. The buffers used were 50 mM acetate buffer (black triangle) at pH 3.5-5.5, 50 mM MES buffer (black circle) at pH 5.5-7.5, 50 mM Tris-HCl buffer (white circle) at pH 7.5-9.0, and sodium hydrogencarbonate buffer (white triangle) at pH 9.0-11.5. The axis of abscissa of the graph shows pH of α1-6 fucosyltransferase obtained in the present invention and the axis of ordinate shows residual activity (%).

As shown in FIG. 3, the optimum temperature of the enzyme of the present invention was found to be at about 37° C. and the enzyme was considered to retain sufficient activity in the range of 20-40° C. A frozen product thereof was stable at -20° C. for at least several months. The buffer used was 200 mM MES buffer (black circle), pH 7.0. The axis of abscissa of the graph shows treatment temperature (° C.) and the axis of ordinate shows relative activity (%) of the α1-6 fucosyltransferase obtained in the present invention.

While many glycosyltransferases require divalent metal ion for their activity, such as magnesium, manganese and the like, the enzyme showed sufficient activity in the absence of such divalent metal ion. Inasmuch as it showed sufficient activity even in the presence of 5 mM EDTA, which is a chelating agent, it is concluded that the enzyme does not require a divalent metal ion.

EXAMPLE 2

Determination of Amino Terminal Amino Acid Sequence of Porcine Brain α1-6 fucosyltransferase

Purified porcine brain α1-6 fucosyltransferase (5 μg) was subjected to SDS-polyacrylamide gel electrophoresis, after which the protein was transferred to PVDF membrane (Millipore) by electroblotting. The PVDF membrane was stained with Coomassie Brilliant Blue G250, and a single band of porcine brain α1-6 fucosyltransferase was detected at 60 kDa.

Then, the PVDF membrane containing said band was cut out, and, after destaining with 50% methanol, subjected to Biosystem 473A protein sequencer (Applied Biosystems) to determine amino terminal amino acid sequence of α1-6 fucosyltransferase. The amino acid sequence determined is depicted in Sequence Listing, SEQ ID NO:3.

EXAMPLE 3

Determination of Partial Amino Acid Sequence of Porcine Brain α1-6 fucosyltransferase

Purified porcine brain α1-6 fucosyltransferase (13 μg) was subjected to SDS-polyacrylamide gel electrophoresis, after which the protein was transferred to PVDF membrane (Millipore) by electroblotting. The PVDF membrane was stained with Coomassie Brilliant Blue G250, and a single band of porcine brain α1-6 fucosyltransferase was detected at 60 kDa.

Then, the PVDF membrane containing said band was cut out and destained with 50% methanol. Said PVDF membrane section was treated in 100 mM Tris-HCl buffer-5% acetonitrile (pH 8.2) containing 1 μg of lysylendopeptidase, at 37° C. for 12 hours for proteolysis. The PVDF membrane section which underwent proteolysis was ultrasonicated to extract the proteolysis product. The proteolysis product thus obtained was separated by a reversed phase high performance liquid chromatography using a C-18 column to give 3 peptide fragments. The substance containing said peptide fragments, which was separated by the reversed phase high performance liquid chromatography, was applied to polybrene-coated precycled glass fiber filter activated with trifluoroacetate and dried, and then subjected to Biosystem 473A protein sequencer (Applied Biosystems) to determine partial amino acid sequence of porcine brain α1-6 fucosyltransferase. The determined amino acid sequence is depicted in Sequence Listing, SEQ ID NOs:4-6.

EXAMPLE 4

Preparation of Probe DNA by PCR

Mixed primers shown in SEQ ID NO:7 and SEQ ID NO:8 were synthesized from the amino acid sequences obtained in Examples 2 and 3. The mixed primer shown in SEQ ID NO:7 was used as a sense primer, and the mixed primer shown in SEQ ID NO:8 was used as an antisense primer for PCR. To be specific, 25 cycles of PCR were performed wherein PCR at 94° C. (1 min), 55° C. (2 min) and 72° C. (3 min) using 2 pg of porcine brain-derived cDNA, 25 pmole of sense primer (mixed primer shown in SEQ ID NO:7), 25 pmole of antisense primer (mixed primer shown in SEQ ID NO:8) and a reaction mixture (50 μl) of 50 mM potassium chloride-10 mM Tris-HCl buffer (pH 8.3)-1.5 mM magnesium chloride-0.001% gelatin-200 μM dNTP, containing 2.5 units of Taq DNA polymerase was one cycle.

The reaction mixture (10 μl ) after PCR was subjected to 0.7% agarose gel electrophoresis to confirm the PCR reaction product DNA fragments. As a result of PCR performed using a mixed primer shown in SEQ ID NO:7 and a mixed primer shown in SEQ ID NO:8 in combination, a 1.45 kbp DNA fragment was confirmed by agarose gel electrophoresis.

This DNA fragment was subcloned into plasmid pT7BLUEt-Vector (Novagen) and nucleotide sequence was confirmed. As a result, a DNA corresponding to the amino acid sequence depicted in Sequence Listing, SEQ ID NOs:3-6 was detected, whereby the DNA fragment was confirmed to be a part of α1-6 fucosyltransferase gene.

EXAMPLE 5

Isolation of Porcine Brain α1-6 fucosyltransferase Gene

The DNA fragments obtained in Example 4 were labeled with α-³² P dCTP (3000 Ci/mmol, Amersham) and used as a probe to screen clones containing cDNA encoding α1-6 fucosyltransferase, from porcine brain-derived λgt11 cDNA library (Clonetech) by plaque hybridization method.

As a result of screening of about 400,000 plaques, 5 positive clones c1, c2, c3, c4 and c5 were obtained. Said clones c1 and c2 were postulated to contain a full length α1-6 fucosyltransferase gene in view of their length. Thus, the nucleotide sequences of c1 and c2 were determined, and a nucleotide sequence depicted in SEQ ID NO:1 was obtained.

EXAMPLE 6

Expression of Porcine Brain α1-6 fucosyltransferase Gene

The coding region of α1-6 fucosyltransferase gene was subcloned into expression vector pSVK3 from clones containing cDNA encoding porcine brain α1-6 fucosyltransferase obtained in Example 5. The expression vector containing said α1-6 fucosyltransferase gene was introduced into COS-1 cells. After 48 hours of incubation, culture cells were collected and the cells were disrupted. The enzyme activity of α1-6 fucosyltransferase in the obtained lysate was determined.

As a control, the enzyme activity of α1-6 fucosyltransferase in the lysate of COS-1 cells, into which mock pSVK3 had been introduced, was determined. As a result, the control hardly showed activity, whereas COS-cells into which the expression vector containing said α1-6 fucosyltransferase gene had been introduced, showed a high activity of 2360 nmole/h/mg protein.

EXAMPLE 7

(1) Preparation of Crude Enzyme Solution from Serum-free Culture Medium of Human Gastric Cancer Cell MKN45

Human gastric cancer cell MKN45 was cultured in a serum-free medium (RPMI1640 medium:Ham's F-12 medium=1:1) containing sodium selenite and canamycin, at 37° C. in 5% CO₂. The resulting serum-free culture medium (100 l) was concentrated to 2 l by ultrafiltration. The buffer was changed to a Tris-HCl buffer containing 5 mM 2-mercaptoethanol and 0.1% CHAPS [3-((3-cholamidopropyl)dimethylammonio)-1-propanesulfonate], pH 7.5, to give a crude enzyme solution. This crude enzyme solution was subjected to column chromatography using Q-sepharose, GDP-hexanolamine-sepharose, (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-asparagine-sepharose and the like to collect active fractions, from which the human α1-6 fucosyltransferase of the present invention could be purified.

(2) Preparation of Enzyme

The crude enzyme solution obtained in (1) above was subjected to the following purification steps. That is, the solution was applied to a Q-sepharose column equilibrated with Tris-HCl buffer containing 5 mM 2-mercaptoethanol and 0.1% CHAPS, pH 7.5. The column was washed with a 5-fold amount of the same buffer and the active fractions eluted with the same buffer containing 0.1 M NaCl were collected. The active fractions were concentrated using an ultrafiltration membrane and the buffer was changed to Tris-HCl buffer containing 5 mM 2-mercaptoethanol and 0.7% CHAPS, pH 7.5, after which the fractions were applied to GDP-hexanolamine-sepharose column equilibrated with the same buffer. The elution was performed by the linear gradient of NaCl from 0 M to 0.5 M.

The active fractions from 0.15 M to 0.3 M were collected and Concentrated using an ultrafiltration membrane. After desalting, the fractions were applied to a (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-asparagine-sepharose column equilibrated with Tris-HCl buffer containing 5 mM 2-mercaptoethanol and 0.7% CHAPS, pH 7.5. The elution was performed by the linear gradient of NaCl from 0 M to 0.5 M.

The active fractions from 0.2 M to 0.5 M were collected and concentrated using an ultrafiltration membrane. Desalting gave human α1-6 fucosyltransferase.

The thus-obtained human α1-6 fucosyltransferase fractions showed a single band at a molecular weight of about 60,000 by SDS-polyacrylamide gel electrophoresis. No other activities, such as those of transferase and glycosidase, were found and this purified enzyme was sufficiently usable as a reagent for sugar chain studies.

The optimum pH (determined by changing the pH of buffer) of the enzyme of the present invention is shown in FIG. 4. The enzyme showed high activity at around pH 7.0-7.5. In this graph, the black circle shows the case when MES buffer was used and white circle shows the case when Tris-HCl buffer was used.

The pH stability of the enzyme of the present invention was examined in the same manner. FIG. 5 shows residual activity after treating the enzyme in each buffer at each pH, 4° C. for 5 hours. The enzyme was comparatively stable at about pH 4-10, and particularly stable at pH 5-9. In this graph, the black triangle shows the case when acetate buffer was used, the black circle shows the case when MES buffer was used, the white circle shows the case when Tris-HCl buffer was used, and the white triangle shows the case when sodium hydrogencarbonate buffer was used.

As shown in FIG. 6, the optimum temperature of the enzyme of the present invention was found to be at about 37° C. and the enzyme was considered to retain sufficient activity in the range of 20-40° C. The frozen product was stable at -20° C. for at least several months.

The enzyme showed sufficient activity in the absence of divalent metal ion. Inasmuch as it showed sufficient activity even in the presence of 5 mM EDTA, which is a chelating agent, it is concluded that the enzyme does not require a divalent metal ion.

EXAMPLE 8

Determination of Amino Acid Sequence of Human α1-6 fucosyltransferase

Purified human α1-6 fucosyltransferase (1 μg) was subjected to SDS-polyacrylamide gel electrophoresis, after which the protein was transferred to PVDF membrane (Millipore) by electroblotting. The PVDF membrane was stained with Coomassie Brilliant Blue G250, and a single band of α1-6 fucosyltransferase was detected at about 60 kDa. Then, the PVDF membrane containing said band was cut out, and, after destaining with 50% methanol, subjected to Biosystem 473A protein sequencer (Applied Biosystems) to determine amino terminal amino acid sequence of human α1-6 fucosyltransferase. The amino acid sequence determined is depicted in Sequence Listing, SEQ ID NO:11.

EXAMPLE 9

Determination of Partial Amino Acid Sequence of Human α1-6 fucosyltransferase

Purified human α1-6 fucosyltransferase (5 μg) was mixed with lysine endopeptidase and subjected to SDS-polyacrylamide gel electrophoresis, after which the peptide fragments were transferred to PVDF membrane (Millipore) by electroblotting. The PVDF membrane was stained with Coomassie Brilliant Blue G250, and several bands containing peptide fragments, inclusive of two main bands, were detected. Then, the PVDF membrane containing each main band was cut out and destained with 50% methanol. Said membrane was subjected to Biosystem 473A protein sequencer (Applied Biosystems) to determine the internal partial amino acid sequence of human α1-6 fucosyltransferase. The determined amino acid sequences are depicted in Sequence Listing, SEQ ID NO:12 and SEQ ID NO:13.

EXAMPLE 10

Preparation of Probe DNA by PCR

Mixed primers shown by SEQ ID NO:14 and SEQ ID NO:15 were synthesized from the amino acid sequences obtained in Example 9. The mixed primer shown in SEQ ID NO:14 was used as a sense primer, and the mixed primer shown in SEQ ID NO:15 was used as an antisense primer for PCR. To be specific, 36 cycles of PCR were performed wherein PCR at 94° C. (30 sec), 46° C. (30 sec) and 72° C. (1.5 min) using 2 μg of human-derived cDNA, 25 pmole of sense primer (mixed primer shown in SEQ ID NO: 14), 25 pmole of antisense primer (mixed primer shown in SEQ ID NO:15) and a reaction mixture (50 μl) of 50 mM potassium chloride-10 mM Tris-HCl buffer (pH 8.3)-1.5 mM magnesium chloride-0.001% gelatin-200 μM dNTP, containing 2.5 units of Taq DNA polymerase, was one cycle.

The reaction mixture (10 μl) after PCR was subjected to 2.0% agarose gel electrophoresis to confirm the PCR reaction product DNA fragments. As a result, about 200 bp DNA fragment was confirmed by agarose gel electrophoresis.

This DNA fragment was subcloned into plasmid pT7BLUEt-Vector (Novagen) and the nucleotide sequence was confirmed. As a result, the DNA fragment was found to encode the amino acid sequence depicted in Sequence Listing, SEQ ID NO:12 and SEQ ID NO:13, whereby the DNA fragment was confirmed to be a part of α1-6 fucosyltransferase gene.

EXAMPLE 11

Isolation of Human α1-6 fucosyltransferase Gene

The DNA fragment obtained in Example 10 was labeled with [α-³² P]dCTP (3000 Ci/mmol, Amersham) and used as a probe to screen clones containing cDNA encoding human α1-6 fucosyltransferase, from human gastric cancer cell MKN45-derived λZAP cDNA library by plaque hybridization method. As a result of screening of about 2,000,000 plaques, 8 positive clones c1 to c8 were obtained. Said clones c1 to c7 were postulated to contain a full length α1-6 fucosyltransferase gene in view of the restriction enzyme cleavage site and their length. The nucleotide sequences of c1 and c2 were determined, as a result of which a nucleotide sequence depicted in SEQ ID NO:9 was obtained.

EXAMPLE 12

Expression of Human α1-6 fucosyltransferase

The coding region of human α1-6 fucosyltransferase gene was subcloned into expression vector pSVK3 from clones containing cDNA encoding the human α1-6 fucosyltransferase obtained in Example 11. An expression vector containing said α1-6 fucosyltransferase gene was introduced into COS-1 cells. After 48 hours of incubation, culture cells were collected and disrupted. The enzyme activity of α1-6 fucosyltransferase in the obtained lysate was determined. As a control, the enzyme activity of α1-6 fucosyltransferase in the lysate of COS-1 cells, into which mock pSVK3 had been introduced, was determined. As a result, the control hardly showed activity, whereas COS-cells, into which the expression vector containing said α1-6 fucosyltransferase gene had been introduced, showed a high activity of 2130 nmole/h/mg protein.

Industrial Applicability

The porcine α1-6 fucosyltransferase of the present invention differs significantly from known human α1-6 fucosyltransferase in physico-chemical properties, and shows activity under optimum reaction conditions which are closer to the physiological conditions.

The α1-6 fucosyltransferase derived from human also shows physico-chemical properties markedly different from those of known human α1-6 fucosyltransferase, showing activity under optimum reaction conditions which are closer to the physiological conditions. Hence, the present invention enables development of glyco-technology inclusive of modification and synthesis of sugar chain, and of a method for diagnosis of diseases, such as cancer, which includes the use of an antibody specific for the enzyme of the present invention or the gene thereof.

    __________________________________________________________________________     #             SEQUENCE LISTING                                                    - -  - - (1) GENERAL INFORMATION:                                              - -    (iii) NUMBER OF SEQUENCES: 15                                           - -  - - (2) INFORMATION FOR SEQ ID NO:1:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 1728 base - #pairs                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: double                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: cDNA                                               - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                - - ATG CGG CCA TGG ACT GGT TCG TGG CGT TGG AT - #T ATG CTC ATT CTT         TTT       48                                                                     Met Arg Pro Trp Thr Gly Ser Trp Arg Trp Il - #e Met Leu Ile Leu Phe                             - #5                  - #10                  - #15            - - GCC TGG GGG ACC TTG CTA TTT TAC ATA GGT GG - #T CAC TTG GTA CGA GAT            96                                                                        Ala Trp Gly Thr Leu Leu Phe Tyr Ile Gly Gl - #y His Leu Val Arg Asp                         20     - #             25     - #             30                   - - AAT GAC CAC TCT GAT CAC TCT AGC CGA GAA CT - #G TCC AAG ATT TTG GCA           144                                                                        Asn Asp His Ser Asp His Ser Ser Arg Glu Le - #u Ser Lys Ile Leu Ala                     35         - #         40         - #         45                       - - AAG CTG GAA CGC TTA AAA CAA CAA AAT GAA GA - #C TTG AGG AGA ATG GCT           192                                                                        Lys Leu Glu Arg Leu Lys Gln Gln Asn Glu As - #p Leu Arg Arg Met Ala                 50             - #     55             - #     60                           - - GAA TCT CTC CGA ATA CCA GAA GGC CCC ATT GA - #T CAG GGG CCA GCT TCA           240                                                                        Glu Ser Leu Arg Ile Pro Glu Gly Pro Ile As - #p Gln Gly Pro Ala Ser             65                 - # 70                 - # 75                 - # 80        - - GGA AGA GTT CGT GCT TTA GAA GAG CAA TTT AT - #G AAG GCC AAA GAA CAG           288                                                                        Gly Arg Val Arg Ala Leu Glu Glu Gln Phe Me - #t Lys Ala Lys Glu Gln                             85 - #                 90 - #                 95               - - ATT GAA AAT TAT AAG AAA CAA ACT AAA AAT GG - #T CCA GGG AAG GAT CAT           336                                                                        Ile Glu Asn Tyr Lys Lys Gln Thr Lys Asn Gl - #y Pro Gly Lys Asp His                        100      - #           105      - #           110                   - - GAA ATC CTA AGG AGG AGG ATT GAA AAT GGA GC - #T AAA GAG CTC TGG TTT           384                                                                        Glu Ile Leu Arg Arg Arg Ile Glu Asn Gly Al - #a Lys Glu Leu Trp Phe                    115          - #       120          - #       125                       - - TTT CTA CAA AGT GAG TTG AAG AAA TTA AAG AA - #T TTA GAA GGA AAT GAA           432                                                                        Phe Leu Gln Ser Glu Leu Lys Lys Leu Lys As - #n Leu Glu Gly Asn Glu                130              - #   135              - #   140                           - - CTC CAA AGA CAT GCA GAT GAA TTT CTA TCA GA - #T TTG GGA CAT CAT GAA           480                                                                        Leu Gln Arg His Ala Asp Glu Phe Leu Ser As - #p Leu Gly His His Glu            145                 1 - #50                 1 - #55                 1 -       #60                                                                               - - AGG TCT ATA ATG ACG GAT CTA TAC TAC CTC AG - #T CAA ACA GAT GGG         GCA      528                                                                     Arg Ser Ile Met Thr Asp Leu Tyr Tyr Leu Se - #r Gln Thr Asp Gly Ala                           165  - #               170  - #               175               - - GGT GAT TGG CGT GAA AAG GAG GCC AAA GAT CT - #G ACA GAG CTG GTC CAG           576                                                                        Gly Asp Trp Arg Glu Lys Glu Ala Lys Asp Le - #u Thr Glu Leu Val Gln                        180      - #           185      - #           190                   - - CGG AGA ATA ACA TAT CTT CAG AAT CCC AAG GA - #C TGC AGC AAA GCC AAG           624                                                                        Arg Arg Ile Thr Tyr Leu Gln Asn Pro Lys As - #p Cys Ser Lys Ala Lys                    195          - #       200          - #       205                       - - AAG CTA GTG TGT AAT ATC AAC AAA GGC TGT GG - #C TAT GGC TGT CAG CTC           672                                                                        Lys Leu Val Cys Asn Ile Asn Lys Gly Cys Gl - #y Tyr Gly Cys Gln Leu                210              - #   215              - #   220                           - - CAT CAT GTA GTG TAC TGC TTT ATG ATT GCA TA - #T GGC ACC CAG CGA ACA           720                                                                        His His Val Val Tyr Cys Phe Met Ile Ala Ty - #r Gly Thr Gln Arg Thr            225                 2 - #30                 2 - #35                 2 -       #40                                                                               - - CTC GCC TTG GAA TCT CAC AAT TGG CGC TAC GC - #T ACT GGG GGA TGG         GAA      768                                                                     Leu Ala Leu Glu Ser His Asn Trp Arg Tyr Al - #a Thr Gly Gly Trp Glu                           245  - #               250  - #               255               - - ACT GTG TTT AGA CCT GTA AGT GAG ACG TGC AC - #A GAC AGA TCT GGC AGC           816                                                                        Thr Val Phe Arg Pro Val Ser Glu Thr Cys Th - #r Asp Arg Ser Gly Ser                        260      - #           265      - #           270                   - - TCC ACT GGA CAT TGG TCA GGT GAA GTA AAG GA - #C AAA AAT GTT CAG GTG           864                                                                        Ser Thr Gly His Trp Ser Gly Glu Val Lys As - #p Lys Asn Val Gln Val                    275          - #       280          - #       285                       - - GTT GAG CTC CCC ATT GTA GAC AGT GTT CAT CC - #T CGT CCT CCA TAT TTA           912                                                                        Val Glu Leu Pro Ile Val Asp Ser Val His Pr - #o Arg Pro Pro Tyr Leu                290              - #   295              - #   300                           - - CCC CTG GCT GTC CCA GAA GAC CTT GCA GAT CG - #A CTT GTA CGA GTC CAT           960                                                                        Pro Leu Ala Val Pro Glu Asp Leu Ala Asp Ar - #g Leu Val Arg Val His            305                 3 - #10                 3 - #15                 3 -       #20                                                                               - - GGT GAT CCT GCA GTG TGG TGG GTA TCC CAG TT - #T GTC AAG TAC TTG         ATT     1008                                                                     Gly Asp Pro Ala Val Trp Trp Val Ser Gln Ph - #e Val Lys Tyr Leu Ile                           325  - #               330  - #               335               - - CGC CCA CAA CCC TGG CTG GAA AAG GAA ATA GA - #A GAG GCC ACC AAG AAG          1056                                                                        Arg Pro Gln Pro Trp Leu Glu Lys Glu Ile Gl - #u Glu Ala Thr Lys Lys                        340      - #           345      - #           350                   - - CTA GGC TTC AAA CAT CCA GTT ATT GGA GTC CA - #T GTT AGA CGC ACA GAC          1104                                                                        Leu Gly Phe Lys His Pro Val Ile Gly Val Hi - #s Val Arg Arg Thr Asp                    355          - #       360          - #       365                       - - AAA GTG GGA GCG GAA GCA GCC TTC CAT CCC AT - #T GAG GAA TAC ACG GTG          1152                                                                        Lys Val Gly Ala Glu Ala Ala Phe His Pro Il - #e Glu Glu Tyr Thr Val                370              - #   375              - #   380                           - - CAC GTT GAA GAA GAC TTT CAG CTT CTT GCT CG - #C AGA ATG CAA GTG GAT          1200                                                                        His Val Glu Glu Asp Phe Gln Leu Leu Ala Ar - #g Arg Met Gln Val Asp            385                 3 - #90                 3 - #95                 4 -       #00                                                                               - - AAA AAA AGG GTG TAT TTG GCC ACA GAT GAC CC - #T GCT TTG TTA AAA         GAG     1248                                                                     Lys Lys Arg Val Tyr Leu Ala Thr Asp Asp Pr - #o Ala Leu Leu Lys Glu                           405  - #               410  - #               415               - - GCA AAA ACA AAG TAC CCC AGT TAT GAA TTT AT - #T AGT GAT AAC TCT ATC          1296                                                                        Ala Lys Thr Lys Tyr Pro Ser Tyr Glu Phe Il - #e Ser Asp Asn Ser Ile                        420      - #           425      - #           430                   - - TCT TGG TCA GCT GGA CTA CAT AAT CGA TAT AC - #A GAA AAT TCA CTT CGG          1344                                                                        Ser Trp Ser Ala Gly Leu His Asn Arg Tyr Th - #r Glu Asn Ser Leu Arg                    435          - #       440          - #       445                       - - GGT GTG ATC CTG GAT ATA CAC TTT CTC TCC CA - #G GCA GAC TTC CTA GTG          1392                                                                        Gly Val Ile Leu Asp Ile His Phe Leu Ser Gl - #n Ala Asp Phe Leu Val                450              - #   455              - #   460                           - - TGT ACT TTT TCA TCG CAG GTC TGT AGA GTT GC - #T TAT GAA ATC ATG CAA          1440                                                                        Cys Thr Phe Ser Ser Gln Val Cys Arg Val Al - #a Tyr Glu Ile Met Gln            465                 4 - #70                 4 - #75                 4 -       #80                                                                               - - GCG CTG CAT CCT GAT GCC TCT GCG AAC TTC CG - #T TCT TTG GAT GAC         ATC     1488                                                                     Ala Leu His Pro Asp Ala Ser Ala Asn Phe Ar - #g Ser Leu Asp Asp Ile                           485  - #               490  - #               495               - - TAC TAT TTT GGA GGC CCA AAT GCC CAC AAC CA - #A ATT GCC ATT TAT CCT          1536                                                                        Tyr Tyr Phe Gly Gly Pro Asn Ala His Asn Gl - #n Ile Ala Ile Tyr Pro                        500      - #           505      - #           510                   - - CAC CAA CCT CGA ACT GAA GGA GAA ATC CCC AT - #G GAA CCT GGA GAT ATT          1584                                                                        His Gln Pro Arg Thr Glu Gly Glu Ile Pro Me - #t Glu Pro Gly Asp Ile                    515          - #       520          - #       525                       - - ATT GGT GTG GCT GGA AAT CAC TGG GAT GGC TA - #T CCT AAA GGT GTT AAC          1632                                                                        Ile Gly Val Ala Gly Asn His Trp Asp Gly Ty - #r Pro Lys Gly Val Asn                530              - #   535              - #   540                           - - AGA AAA CTG GGA AGG ACG GGC CTA TAT CCC TC - #C TAC AAA GTT CGA GAG          1680                                                                        Arg Lys Leu Gly Arg Thr Gly Leu Tyr Pro Se - #r Tyr Lys Val Arg Glu            545                 5 - #50                 5 - #55                 5 -       #60                                                                               - - AAG ATA GAA ACA GTC AAG TAC CCC ACA TAT CC - #C GAG GCT GAC AAG         TAA     1728                                                                     Lys Ile Glu Thr Val Lys Tyr Pro Thr Tyr Pr - #o Glu Ala Asp Lys                               565  - #               570  - #               575               - -  - - (2) INFORMATION FOR SEQ ID NO:2:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH:575 amino ac - #ids                                                 (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: protein                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                - - Met Arg Pro Trp Thr Gly Ser Trp Arg Trp Il - #e Met Leu Ile Leu Phe                         - #5                  - #10                  - #15            - - Ala Trp Gly Thr Leu Leu Phe Tyr Ile Gly Gl - #y His Leu Val Arg Asp                    20     - #             25     - #             30                   - - Asn Asp His Ser Asp His Ser Ser Arg Glu Le - #u Ser Lys Ile Leu Ala                35         - #         40         - #         45                       - - Lys Leu Glu Arg Leu Lys Gln Gln Asn Glu As - #p Leu Arg Arg Met Ala            50             - #     55             - #     60                           - - Glu Ser Leu Arg Ile Pro Glu Gly Pro Ile As - #p Gln Gly Pro Ala Ser        65                 - # 70                 - # 75                 - # 80        - - Gly Arg Val Arg Ala Leu Glu Glu Gln Phe Me - #t Lys Ala Lys Glu Gln                        85 - #                 90 - #                 95               - - Ile Glu Asn Tyr Lys Lys Gln Thr Lys Asn Gl - #y Pro Gly Lys Asp His                   100      - #           105      - #           110                   - - Glu Ile Leu Arg Arg Arg Ile Glu Asn Gly Al - #a Lys Glu Leu Trp Phe               115          - #       120          - #       125                       - - Phe Leu Gln Ser Glu Leu Lys Lys Leu Lys As - #n Leu Glu Gly Asn Glu           130              - #   135              - #   140                           - - Leu Gln Arg His Ala Asp Glu Phe Leu Ser As - #p Leu Gly His His Glu       145                 1 - #50                 1 - #55                 1 -       #60                                                                               - - Arg Ser Ile Met Thr Asp Leu Tyr Tyr Leu Se - #r Gln Thr Asp Gly         Ala                                                                                              165  - #               170  - #               175              - - Gly Asp Trp Arg Glu Lys Glu Ala Lys Asp Le - #u Thr Glu Leu Val Gln                   180      - #           185      - #           190                   - - Arg Arg Ile Thr Tyr Leu Gln Asn Pro Lys As - #p Cys Ser Lys Ala Lys               195          - #       200          - #       205                       - - Lys Leu Val Cys Asn Ile Asn Lys Gly Cys Gl - #y Tyr Gly Cys Gln Leu           210              - #   215              - #   220                           - - His His Val Val Tyr Cys Phe Met Ile Ala Ty - #r Gly Thr Gln Arg Thr       225                 2 - #30                 2 - #35                 2 -       #40                                                                               - - Leu Ala Leu Glu Ser His Asn Trp Arg Tyr Al - #a Thr Gly Gly Trp         Glu                                                                                              245  - #               250  - #               255              - - Thr Val Phe Arg Pro Val Ser Glu Thr Cys Th - #r Asp Arg Ser Gly Ser                   260      - #           265      - #           270                   - - Ser Thr Gly His Trp Ser Gly Glu Val Lys As - #p Lys Asn Val Gln Val               275          - #       280          - #       285                       - - Val Glu Leu Pro Ile Val Asp Ser Val His Pr - #o Arg Pro Pro Tyr Leu           290              - #   295              - #   300                           - - Pro Leu Ala Val Pro Glu Asp Leu Ala Asp Ar - #g Leu Val Arg Val His       305                 3 - #10                 3 - #15                 3 -       #20                                                                               - - Gly Asp Pro Ala Val Trp Trp Val Ser Gln Ph - #e Val Lys Tyr Leu         Ile                                                                                              325  - #               330  - #               335              - - Arg Pro Gln Pro Trp Leu Glu Lys Glu Ile Gl - #u Glu Ala Thr Lys Lys                   340      - #           345      - #           350                   - - Leu Gly Phe Lys His Pro Val Ile Gly Val Hi - #s Val Arg Arg Thr Asp               355          - #       360          - #       365                       - - Lys Val Gly Ala Glu Ala Ala Phe His Pro Il - #e Glu Glu Tyr Thr Val           370              - #   375              - #   380                           - - His Val Glu Glu Asp Phe Gln Leu Leu Ala Ar - #g Arg Met Gln Val Asp       385                 3 - #90                 3 - #95                 4 -       #00                                                                               - - Lys Lys Arg Val Tyr Leu Ala Thr Asp Asp Pr - #o Ala Leu Leu Lys         Glu                                                                                              405  - #               410  - #               415              - - Ala Lys Thr Lys Tyr Pro Ser Tyr Glu Phe Il - #e Ser Asp Asn Ser Ile                   420      - #           425      - #           430                   - - Ser Trp Ser Ala Gly Leu His Asn Arg Tyr Th - #r Glu Asn Ser Leu Arg               435          - #       440          - #       445                       - - Gly Val Ile Leu Asp Ile His Phe Leu Ser Gl - #n Ala Asp Phe Leu Val           450              - #   455              - #   460                           - - Cys Thr Phe Ser Ser Gln Val Cys Arg Val Al - #a Tyr Glu Ile Met Gln       465                 4 - #70                 4 - #75                 4 -       #80                                                                               - - Ala Leu His Pro Asp Ala Ser Ala Asn Phe Ar - #g Ser Leu Asp Asp         Ile                                                                                              485  - #               490  - #               495              - - Tyr Tyr Phe Gly Gly Pro Asn Ala His Asn Gl - #n Ile Ala Ile Tyr Pro                   500      - #           505      - #           510                   - - His Gln Pro Arg Thr Glu Gly Glu Ile Pro Me - #t Glu Pro Gly Asp Ile               515          - #       520          - #       525                       - - Ile Gly Val Ala Gly Asn His Trp Asp Gly Ty - #r Pro Lys Gly Val Asn           530              - #   535              - #   540                           - - Arg Lys Leu Gly Arg Thr Gly Leu Tyr Pro Se - #r Tyr Lys Val Arg Glu       545                 5 - #50                 5 - #55                 5 -       #60                                                                               - - Lys Ile Glu Thr Val Lys Tyr Pro Thr Tyr Pr - #o Glu Ala Asp Lys                          565  - #               570  - #               575               - -  - - (2) INFORMATION FOR SEQ ID NO:3:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 26 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                - - Lys Gln Thr Lys Asn Gly Pro Gly Lys Asp Hi - #s Glu Ile Leu Arg Arg                         - #5                  - #10                  - #15            - - Arg Ile Glu Asn Gly Ala Lys Glu Leu Gln                                                20     - #             25                                          - -  - - (2) INFORMATION FOR SEQ ID NO:4:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 10 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                - - Lys Tyr Pro Thr Tyr Pro Glu Ala Asp Lys                                                     - #5                  - #10                                   - -  - - (2) INFORMATION FOR SEQ ID NO:5:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 12 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                - - Lys Tyr Leu Ile Arg Pro Gln Pro Trp Leu Gl - #u Lys                                         - #5                  - #10                                   - -  - - (2) INFORMATION FOR SEQ ID NO:6:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 14 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                - - Lys Arg Val Tyr Leu Ala Thr Asp Asp Pro Al - #a Leu Leu Lys                                 - #5                  - #10                                   - -  - - (2) INFORMATION FOR SEQ ID NO:7:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 nucleoti - #des                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: DNA                                                - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                - - AARSARACNA ARAAYGGNCC            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:8:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 nucleoti - #des                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: DNA                                                - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                - - TCNGGRTANG TNGGRTAYTT            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:9:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 2100 base - #pairs                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: double                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: cDNA                                               - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                - - AAGCTTCCTA CACATATCAC CAGGAGGATC TCTTTGAAAG ATTCACTGCA GG -              #ACTACCAG     60                                                                  - - AGAGAATAAT TTGTCTGAAG CATCATGTGT TGAAACAACA GAAGTCTATT CA -             #CCTGTGCA    120                                                                  - - CTAACTAGAA ACAGAGTTAC AATGTTTTCA ATTCTTTGAG CTCCAGGACT CC -             #AGGGAAGT    180                                                                  - - GAGTTGAAAA TCTGAAA ATG CGG CCA TGG ACT GGT TCC - #TGG CGT TGG ATT            230                                                                                          - # Met Arg Pro Trp Thr Gly Ser Trp Arg Trp - #Ile                             - #                  - #5                  - # 10             - - ATG CTC ATT CTT TTT GCC TGG GGG ACC TTG CT - #G TTT TAT ATA GGT GGT           278                                                                        Met Leu Ile Leu Phe Ala Trp Gly Thr Leu Le - #u Phe Tyr Ile Gly Gly                         15     - #             20     - #             25                   - - CAC TTG GTA CGA GAT AAT GAC CAT CCT GAT CA - #C TCT AGC CGA GAA CTG           326                                                                        His Leu Val Arg Asp Asn Asp His Pro Asp Hi - #s Ser Ser Arg Glu Leu                     30         - #         35         - #         40                       - - TCC AAG ATT CTG GCA AAG CTT GAA CGC TTA AA - #A CAG CAG AAT GAA GAC           374                                                                        Ser Lys Ile Leu Ala Lys Leu Glu Arg Leu Ly - #s Gln Gln Asn Glu Asp                 45             - #     50             - #     55                           - - TTG AGG CGA ATG GCC GAA TCT CTC CGG ATA CC - #A GAA GGC CCT ATT GAT           422                                                                        Leu Arg Arg Met Ala Glu Ser Leu Arg Ile Pr - #o Glu Gly Pro Ile Asp             60                 - # 65                 - # 70                 - # 75        - - CAG GGG CCA GCT ATA GGA AGA GTA CGC GTT TT - #A GAA GAG CAG CTT GTT           470                                                                        Gln Gly Pro Ala Ile Gly Arg Val Arg Val Le - #u Glu Glu Gln Leu Val                             80 - #                 85 - #                 90               - - AAG GCC AAA GAA CAG ATT GAA AAT TAC AAG AA - #A CAG ACC AGA AAT GGT           518                                                                        Lys Ala Lys Glu Gln Ile Glu Asn Tyr Lys Ly - #s Gln Thr Arg Asn Gly                         95     - #            100     - #            105                   - - CTG GGG AAG GAT CAT GAA ATC CTG AGG AGG AG - #G ATT GAA AAT GGA GCT           566                                                                        Leu Gly Lys Asp His Glu Ile Leu Arg Arg Ar - #g Ile Glu Asn Gly Ala                    110          - #       115          - #       120                       - - AAA GAG CTC TGG TTT TTC CTA CAG AGT GAA TT - #G AAG AAA TTA AAG AAC           614                                                                        Lys Glu Leu Trp Phe Phe Leu Gln Ser Glu Le - #u Lys Lys Leu Lys Asn                125              - #   130              - #   135                           - - TTA GAA GGA AAT GAA CTC CAA AGA CAT GCA GA - #T GAA TTT CTT TTG GAT           662                                                                        Leu Glu Gly Asn Glu Leu Gln Arg His Ala As - #p Glu Phe Leu Leu Asp            140                 1 - #45                 1 - #50                 1 -       #55                                                                               - - TTA GGA CAT CAT GAA AGG TCT ATA ATG ACG GA - #T CTA TAC TAC CTC         AGT      710                                                                     Leu Gly His His Glu Arg Ser Ile Met Thr As - #p Leu Tyr Tyr Leu Ser                           160  - #               165  - #               170               - - CAG ACA GAT GGA GCA GGT GAT TGG CGG GAA AA - #A GAG GCC AAA GAT CTG           758                                                                        Gln Thr Asp Gly Ala Gly Asp Trp Arg Glu Ly - #s Glu Ala Lys Asp Leu                        175      - #           180      - #           185                   - - ACA GAA CTG GTT CAG CGG AGA ATA ACA TAT CT - #T CAG AAT CCC AAG GAC           806                                                                        Thr Glu Leu Val Gln Arg Arg Ile Thr Tyr Le - #u Gln Asn Pro Lys Asp                    190          - #       195          - #       200                       - - TGC AGC AAA GCC AAA AAG CTG GTG TGT AAT AT - #C AAC AAA GGC TGT GGC           854                                                                        Cys Ser Lys Ala Lys Lys Leu Val Cys Asn Il - #e Asn Lys Gly Cys Gly                205              - #   210              - #   215                           - - TAT GGC TGT CAG CTC CAT CAT GTG GTC TAC TG - #C TTC ATG ATT GCA TAT           902                                                                        Tyr Gly Cys Gln Leu His His Val Val Tyr Cy - #s Phe Met Ile Ala Tyr            220                 2 - #25                 2 - #30                 2 -       #35                                                                               - - GGC ACC CAG CGA ACA CTC ATC TTG GAA TCT CA - #G AAT TGG CGC TAT         GCT      950                                                                     Gly Thr Gln Arg Thr Leu Ile Leu Glu Ser Gl - #n Asn Trp Arg Tyr Ala                           240  - #               245  - #               250               - - ACT GGT GGA TGG GAG ACT GTA TTT AGG CCT GT - #A AGT GAG ACA TGC ACA           998                                                                        Thr Gly Gly Trp Glu Thr Val Phe Arg Pro Va - #l Ser Glu Thr Cys Thr                        255      - #           260      - #           265                   - - GAC AGA TCT GGC ATC TCC ACT GGA CAC TGG TC - #A GGT GAA GTG AAG GAC          1046                                                                        Asp Arg Ser Gly Ile Ser Thr Gly His Trp Se - #r Gly Glu Val Lys Asp                    270          - #       275          - #       280                       - - AAA AAT GTT CAA GTG GTC GAG CTT CCC ATT GT - #A GAC AGT CTT CAT CCC          1094                                                                        Lys Asn Val Gln Val Val Glu Leu Pro Ile Va - #l Asp Ser Leu His Pro                285              - #   290              - #   295                           - - CGT CCT CCA TAT TTA CCC TTG GCT GTA CCA GA - #A GAC CTC GCA GAT CGA          1142                                                                        Arg Pro Pro Tyr Leu Pro Leu Ala Val Pro Gl - #u Asp Leu Ala Asp Arg            300                 3 - #05                 3 - #10                 3 -       #15                                                                               - - CTT GTA CGA GTG CAT GGT GAC CCT GCA GTG TG - #G TGG GTG TCT CAG         TTT     1190                                                                     Leu Val Arg Val His Gly Asp Pro Ala Val Tr - #p Trp Val Ser Gln Phe                           320  - #               325  - #               330               - - GTC AAA TAC TTG ATC CGC CCA CAG CCT TGG CT - #A GAA AAA GAA ATA GAA          1238                                                                        Val Lys Tyr Leu Ile Arg Pro Gln Pro Trp Le - #u Glu Lys Glu Ile Glu                        335      - #           340      - #           345                   - - GAA GCC ACC AAG AAG CTT GGC TTC AAA CAT CC - #A GTT ATT GGA GTC CAT          1286                                                                        Glu Ala Thr Lys Lys Leu Gly Phe Lys His Pr - #o Val Ile Gly Val His                    350          - #       355          - #       360                       - - GTC AGA GCG ACA GAC AAA GTG GGA ACA GAA GC - #T GCC TTC CAT CCC ATT          1334                                                                        Val Arg Arg Thr Asp Lys Val Gly Thr Glu Al - #a Ala Phe His Pro Ile                365              - #   370              - #   375                           - - GAA GAG TAC ATG GTG CAT GTT GAA GAA CAT TT - #T CAG CTT CTT GCA CGC          1382                                                                        Glu Glu Tyr Met Val His Val Glu Glu His Ph - #e Gln Leu Leu Ala Arg            380                 3 - #85                 3 - #90                 3 -       #95                                                                               - - AGA ATG CAA GTG GAC AAA AAA AGA GTG TAT TT - #G GCC ACA GAT GAC         CCT     1430                                                                     Arg Met Gln Val Asp Lys Lys Arg Val Tyr Le - #u Ala Thr Asp Asp Pro                           400  - #               405  - #               410               - - TCT TTA TTA AAG GAG GCA AAA ACA AAG TAC CC - #C AAT TAT GAA TTT ATT          1478                                                                        Ser Leu Leu Lys Glu Ala Lys Thr Lys Tyr Pr - #o Asn Tyr Glu Phe Ile                        415      - #           420      - #           425                   - - AGT GAT AAC TCT ATT TCC TGG TCA GCT GGA CT - #G CAC AAT CGA TAC ACA          1526                                                                        Ser Asp Asn Ser Ile Ser Trp Ser Ala Gly Le - #u His Asn Arg Tyr Thr                    430          - #       435          - #       440                       - - GAA AAT TCA CTT CGT GGA GTG ATC CTG GAT AT - #A CAT TTT CTC TCT CAG          1574                                                                        Glu Asn Ser Leu Arg Gly Val Ile Leu Asp Il - #e His Phe Leu Ser Gln                445              - #   450              - #   455                           - - GCA GAC TTC CTA GTG TGT ACT TTT TCA TCC CA - #G GTC TGT CGA GTT GCT          1622                                                                        Ala Asp Phe Leu Val Cys Thr Phe Ser Ser Gl - #n Val Cys Arg Val Ala            460                 4 - #65                 4 - #70                 4 -       #75                                                                               - - TAT GAA ATT ATG CAA ACA CTA CAT CCT GAT GC - #C TCT GCA AAC TTC         CAT     1670                                                                     Tyr Glu Ile Met Gln Thr Leu His Pro Asp Al - #a Ser Ala Asn Phe His                           480  - #               485  - #               490               - - TCT TTA GAT GAC ATC TAC TAT TTT GGG GGC CA - #G AAT GCC CAC AAT CAA          1718                                                                        Ser Leu Asp Asp Ile Tyr Tyr Phe Gly Gly Gl - #n Asn Ala His Asn Gln                        495      - #           500      - #           505                   - - ATT GCC ATT TAT GCT CAC CAA CCC CGA ACT GC - #A GAT GAA ATT CCC ATG          1766                                                                        Ile Ala Ile Tyr Ala His Gln Pro Arg Thr Al - #a Asp Glu Ile Pro Met                    510          - #       515          - #       520                       - - GAA CCT GGA GAT ATC ATT GGT GTG GCT GGA AA - #T CAT TGG GAT GGC TAT          1814                                                                        Glu Pro Gly Asp Ile Ile Gly Val Ala Gly As - #n His Trp Asp Gly Tyr                525              - #   530              - #   535                           - - TCT AAA GGT GTC AAC AGG AAA TTG GGA AGG AC - #G GGC CTA TAT CCC TCC          1862                                                                        Ser Lys Gly Val Asn Arg Lys Leu Gly Arg Th - #r Gly Leu Tyr Pro Ser            540                 5 - #45                 5 - #50                 5 -       #55                                                                               - - TAC AAA GTT CGA GAG AAG ATA GAA ACG GTC AA - #G TAC CCC ACA TAT         CCT     1910                                                                     Tyr Lys Val Arg Glu Lys Ile Glu Thr Val Ly - #s Tyr Pro Thr Tyr Pro                           560  - #               565  - #               570               - - GAG GCT GAG AAA TAA   AGCTCAGATG GAAGAGATAA A - #CGACCAAAC                   1955                                                                        Glu Ala Glu Lys                                                                            575                                                                 - - TCAGTTCGAC CAAACTCAGT TCAAACCATT TCAGCCAAAC TGTAGATGAA GA -              #GGGCTCTG   2015                                                                  - - ATCTAACAAA ATAAGGTTAT ATGAGTAGAT ACTCTCAGCA CCAAGAGCAG CT -             #GGGAACTG   2075                                                                  - - ACATAGGCTT CAATTGGTGG AATTC          - #                  - #                  2100                                                                      - -  - - (2) INFORMATION FOR SEQ ID NO:10:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 575 amino - #acids                                                 (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                               - - Met Arg Pro Trp Thr Gly Ser Trp Arg Trp Il - #e Met Leu Ile Leu Phe                         - #5                  - #10                  - #15            - - Ala Trp Gly Thr Leu Leu Phe Tyr Ile Gly Gl - #y His Leu Val Arg Asp                    20     - #             25     - #             30                   - - Asn Asp His Pro Asp His Ser Ser Arg Glu Le - #u Ser Lys Ile Leu Ala                35         - #         40         - #         45                       - - Lys Leu Glu Arg Leu Lys Gln Gln Asn Glu As - #p Leu Arg Arg Met Ala            50             - #     55             - #     60                           - - Glu Ser Leu Arg Ile Pro Glu Gly Pro Ile As - #p Gln Gly Pro Ala Ile        65                 - # 70                 - # 75                 - # 80        - - Gly Arg Val Arg Val Leu Glu Glu Gln Leu Va - #l Lys Ala Lys Glu Gln                        85 - #                 90 - #                 95               - - Ile Glu Asn Tyr Lys Lys Gln Thr Arg Asn Gl - #y Leu Gly Lys Asp His                   100      - #           105      - #           110                   - - Glu Ile Leu Arg Arg Arg Ile Glu Asn Gly Al - #a Lys Glu Leu Trp Phe               115          - #       120          - #       125                       - - Phe Leu Gln Ser Glu Leu Lys Lys Leu Lys As - #n Leu Glu Gly Asn Glu           130              - #   135              - #   140                           - - Leu Gln Arg His Ala Asp Glu Phe Leu Leu As - #p Leu Gly His His Glu       145                 1 - #50                 1 - #55                 1 -       #60                                                                               - - Arg Ser Ile Met Thr Asp Leu Tyr Tyr Leu Se - #r Gln Thr Asp Gly         Ala                                                                                              165  - #               170  - #               175              - - Gly Asp Trp Arg Glu Lys Glu Ala Lys Asp Le - #u Thr Glu Leu Val Gln                   180      - #           185      - #           190                   - - Arg Arg Ile Thr Tyr Leu Gln Asn Pro Lys As - #p Cys Ser Lys Ala Lys               195          - #       200          - #       205                       - - Lys Leu Val Cys Asn Ile Asn Lys Gly Cys Gl - #y Tyr Gly Cys Gln Leu           210              - #   215              - #   220                           - - His His Val Val Tyr Cys Phe Met Ile Ala Ty - #r Gly Thr Gln Arg Thr       225                 2 - #30                 2 - #35                 2 -       #40                                                                               - - Leu Ile Leu Glu Ser Gln Asn Trp Arg Tyr Al - #a Thr Gly Gly Trp         Glu                                                                                              245  - #               250  - #               255              - - Thr Val Phe Arg Pro Val Ser Glu Thr Cys Th - #r Asp Arg Ser Gly Ile                   260      - #           265      - #           270                   - - Ser Thr Gly His Trp Ser Gly Glu Val Lys As - #p Lys Asn Val Gln Val               275          - #       280          - #       285                       - - Val Glu Leu Pro Ile Val Asp Ser Leu His Pr - #o Arg Pro Pro Tyr Leu           290              - #   295              - #   300                           - - Pro Leu Ala Val Pro Glu Asp Leu Ala Asp Ar - #g Leu Val Arg Val His       305                 3 - #10                 3 - #15                 3 -       #20                                                                               - - Gly Asp Pro Ala Val Trp Trp Val Ser Gln Ph - #e Val Lys Tyr Leu         Ile                                                                                              325  - #               330  - #               335              - - Arg Pro Gln Pro Trp Leu Glu Lys Glu Ile Gl - #u Glu Ala Thr Lys Lys                   340      - #           345      - #           350                   - - Leu Gly Phe Lys His Pro Val Ile Gly Val Hi - #s Val Arg Arg Thr Asp               355          - #       360          - #       365                       - - Lys Val Gly Thr Glu Ala Ala Phe His Pro Il - #e Glu Glu Tyr Met Val           370              - #   375              - #   380                           - - His Val Glu Glu His Phe Gln Leu Leu Ala Ar - #g Arg Met Gln Val Asp       385                 3 - #90                 3 - #95                 4 -       #00                                                                               - - Lys Lys Arg Val Tyr Leu Ala Thr Asp Asp Pr - #o Ser Leu Leu Lys         Glu                                                                                              405  - #               410  - #               415              - - Ala Lys Thr Lys Tyr Pro Asn Tyr Glu Phe Il - #e Ser Asp Asn Ser Ile                   420      - #           425      - #           430                   - - Ser Trp Ser Ala Gly Leu His Asn Arg Tyr Th - #r Glu Asn Ser Leu Arg               435          - #       440          - #       445                       - - Gly Val Ile Leu Asp Ile His Phe Leu Ser Gl - #n Ala Asp Phe Leu Val           450              - #   455              - #   460                           - - Cys Thr Phe Ser Ser Gln Val Cys Arg Val Al - #a Tyr Glu Ile Met Gln       465                 4 - #70                 4 - #75                 4 -       #80                                                                               - - Thr Leu His Pro Asp Ala Ser Ala Asn Phe Hi - #s Ser Leu Asp Asp         Ile                                                                                              485  - #               490  - #               495              - - Tyr Tyr Phe Gly Gly Gln Asn Ala His Asn Gl - #n Ile Ala Ile Tyr Ala                   500      - #           505      - #           510                   - - His Gln Pro Arg Thr Ala Asp Glu Ile Pro Me - #t Glu Pro Gly Asp Ile               515          - #       520          - #       525                       - - Ile Gly Val Ala Gly Asn His Trp Asp Gly Ty - #r Ser Lys Gly Val Asn           530              - #   535              - #   540                           - - Arg Lys Leu Gly Arg Thr Gly Leu Tyr Pro Se - #r Tyr Lys Val Arg Glu       545                 5 - #50                 5 - #55                 5 -       #60                                                                               - - Lys Ile Glu Thr Val Lys Tyr Pro Thr Tyr Pr - #o Glu Ala Glu Lys                          565  - #               570  - #               575               - -  - - (2) INFORMATION FOR SEQ ID NO:11:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 14 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                               - - Arg Ile Pro Glu Gly Pro Ile Asp Gln Gly Pr - #o Ala Ile Gly                                 - #5                  - #10                                   - -  - - (2) INFORMATION FOR SEQ ID NO:12:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 25 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                               - - Lys Leu Gly Phe Lys His Pro Val Ile Gly Va - #l His Val Arg Arg Thr                         - #5                  - #10                  - #15            - - Asp Lys Val Gly Thr Glu Ala Ala Phe                                                    20     - #             25                                          - -  - - (2) INFORMATION FOR SEQ ID NO:13:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 13 amino - #acids                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: peptide                                            - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:                               - - Thr Lys Tyr Pro Asn Tyr Glu Phe Ile Ser As - #p Asn Ser                                     - #5                  - #10                                   - -  - - (2) INFORMATION FOR SEQ ID NO:14:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 nucleoti - #des                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: DNA                                                - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:                               - - TTYAARCAYC CHGTBATYGG            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:15:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 nucleoti - #des                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: DNA                                                - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:                               - - GWRTTRTCRG WRATRAAYTC            - #                  - #                       - # 20                                                                  __________________________________________________________________________ 

What is claimed is:
 1. An isolated, human α1-6 fucosyltransferase having the following physico-chemical properties:(1) action: transferring fucose from guanosine diphosphate-fucose to a hydroxy group at the 6-position of the GlcNAc closest to R of a receptor (GlcNAcβ1-2Manα1-6)(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc-R wherein R is an asparagine residue or a peptide chain carrying said residue, whereby to form (GlcNAcβ1-2Man α1-6)-(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fuc.alpha.1-6)GlcNAc-R (2) optimum pH: about 7.5 (3) pH stability: retains activity after 5 hours of treatment at 4° C. at a pH range of 4.0-10.0 (4) optimum temperature: about 30-37° C. (5) inhibition or activation: no requirement for divalent metal for expression of activity; no inhibition of activity in the presence of 5 mM EDTA (6) molecular weight: about 60,000 by SDS-polyacrylamide gel electrophoresis.
 2. The α1-6 fucosyltransferase of claim 1, which is purified from a human cell culture medium.
 3. The α1-6 fucosyltransferase of claim 2, wherein the human cell culture medium is a human gastric cancer cell serum-free medium.
 4. The α1-6 fucosyltransferase of claim 1, which is recombinantly produced. 